1. Field of the Invention
The present invention relates to a fuel injection apparatus used in a marine engine such as an outboard motor for sailing on the sea.
2. Description of Conventional Art
A description will be given of a first example of a conventional fuel injection apparatus for the marine engine with reference to FIG. 4.
Reference symbol T denotes a fuel tank in which fuel is stored, reference symbol V denotes a vapor separator within which a fixed fuel liquid surface Xxe2x80x94X is formed, and reference symbol D denotes a fuel distribution pipe provided with fuel injection valves J injecting and supplying the fuel into an intake pipe of the engine.
Further, the vapor separator V is structured as follows.
Reference numeral 20 denotes a casing formed by a chamber 21 and a cover 22. The chamber 21 is formed in a cup shape with a upper mounting collar portion 21A and a lower closed end, the cover 22 is formed in a cup shape from a lower mounting collar portion 22A and an upper closed end, and a fuel storage space is formed by bringing the respective mounting collar portions 21A and 22A of the chambers 21 and the cover 22 into contact with each other.
Reference symbol F denotes a fixed liquid surface control mechanism which forms and keeps the fixed fuel liquid surface Xxe2x80x94X within the vapor separator V. The fixed liquid surface control mechanism F is constituted by a valve seat 24 which is connected to an inflow passage 23 formed in the cover 22 and is open to the inside of the vapor separator V, a float valve 25 which opens and closes the valve seat 24, and a float 27 which is rotatably supported to an axis 26, swings in correspondence to a liquid surface height formed within the vapor separator V, and controls so as to open and close the valve seat 24 via the float valve 25.
Further, a high pressure fuel pump HP is arranged within the vapor separator V, and this fuel pump HP is constituted by a motor portion and a pump portion.
The fuel pump HP is provided with a fuel discharge hole 28 and a fuel suction hole 29, the fuel suction hole 29 is arranged so as to be below the fuel liquid surface Xxe2x80x94X within the vapor separator V, and the fuel discharge hole 28 is arranged so as to be connected to a fuel discharge passage 30 provided in the cover 22.
Reference symbol R denotes a pressure regulator which regulates a fuel pressure to a predetermined pressure. The pressure regulator R is structured as follows. A diaphragm 33 is clamped between a lower housing 31 and an upper housing 32, a fuel chamber 34 is formed by the diaphragm 33 and the lower housing 31, and a spring chamber 35 is formed by the diaphragm 33 and the upper housing 32.
Further, a fuel inflow hole 36 and a return fuel hole 37 are open to the fuel chamber 34, and a return valve seat 38 is provided in an open end of the return fuel hole 37 to the fuel chamber 34.
An opening of the return valve seat 38 to the fuel chamber 34 is controlled by a valve body 39 which is synchronously moved together with the diaphragm 33.
Further, a spring 40 pressing the diaphragm 33 toward the fuel chamber 34 is provided compressedly within the spring chamber 35, and a vent hole 41 is open to the spring chamber 35. Further, the pressure regulator R is arranged on a top surface of the cover 22, and at this time, the fuel in flow hole 36 is arranged so as to be connected to a pressure fuel inflow passage 42 formed in the cover 22, and the return fuel hole 37 is arranged so as to be open to an inside of the vapor separator V.
The vapor separator V provided with the pressure regulator R mentioned above is connected to the other structures by passages in accordance with the following manner.
The fuel tank T and the inflow passage 23 of the vapor separator V are connected by a fuel inflow pipe 43, and a low pressure fuel pump LP is arranged in the fuel inflow pipe 43.
The fuel discharge passage 30 formed in the vapor separator V and connected to the fuel discharge hole 28 of the high pressure fuel pump HP is connected to the fuel distribution pipe D by a fuel discharge pipe 44.
The pressure fuel inflow passage 42 formed in the cover 22 and connected to the fuel inflow hole 36 of the pressure regulator R is connected to the fuel discharge pipe 44 by a regulator fuel pipe 45.
In accordance with the structure mentioned above, pressure of the fuel within the fuel tank T is increased by the low pressure fuel pump LP, and the fuel having the increased pressure is supplied into the casing 20 of the vapor separator V via the fuel inflow pipe 43, the inflow passage 23 and the valve seat 24, and forms and keeps the fixed fuel liquid surface Xxe2x80x94X within the casing 20 by the fixed liquid surface control mechanism F constituted by the valve seat 24, the float valve 25 and the float 27.
On the other hand, pressure of the fuel stored within the vapor separator V is increased in pressure by the high pressure fuel pump HP, and is supplied into the fuel distribution pipe D via the fuel discharge hole 28, the fuel discharge passage 30 and the fuel discharge pipe 44, and at this time, the pressure of the fuel moving toward the fuel distribution pipe D is regulated to a predetermined pressure by the pressure regulator R.
That is, a part of the fuel flowing within the fuel discharge pipe 44 flows into the fuel chamber 34 of the pressure regulator R via the regulator fuel pipe 45, the pressure fuel inflow pipe 42 and the fuel inflow hole 36, is filled in the fuel chamber 34 so as to press up the valve body 39 via the diaphragm 33, and balances with a spring force of the spring 40 at set pressure (predetermined pressure), whereby it is possible to regulate the pressure of the fuel flowing within the fuel discharge pipe 44 to predetermined pressure.
On the other hand, the valve body 39 is moved upward, whereby the return valve seat 30 is released. Accordingly, the fuel within the fuel chamber 34 is discharged into the casing 20 of the vapor separator V via the return fuel hole 37.
A second example of the conventional fuel injection apparatus for the marine engine is shown in FIG. 5.
In this case, the same reference symbols are attached to the same structure parts as those in FIG. 4, and a description thereof will be omitted.
The second example is different from the first example in view of an arrangement of the pressure regulator R.
That is, the pressure regulator R is arranged within the casing 20 of the vapor separator V and at a position below the fixed fuel liquid surface Xxe2x80x94X, and the lower housing 31 is arranged in a bottom portion 21B of the chamber 21.
Further, the pressure fuel inflow passage 42 provided in the chamber 21 connected to the fuel inflow hole 36 of the pressure regulator R is connected to the fuel distribution pipe D by the regulator fuel pipe 45.
Accordingly, the pressure of fuel flowing within the fuel distribution pipe D is controlled to predetermined fuel pressure by a pressure regulating operation of the pressure regulator R.
In accordance with the first example of the conventional fuel injection apparatus, the pressure regulator R is arranged on the cover 22 of the vapor separator V, whereby the following problems are generated.
That is, since at least upper housing 32 of the pressure regulator R protrudes from the cover 22 and is arranged so as to be directly exposed to the ambient air, it is necessary to apply a corrosion resisting or rust proofing treatment to the upper housing 32 or use a corrosion resisting material for the upper housing 32, whereby it is impossible to effectively reduce a manufacturing cost for the upper housing 32.
Further, since the vent hole 41 is pierced so as to be open to the upper housing 32, there is a risk that sea water enters into the spring chamber 35 of the pressure regulator R from the vent hole 41, whereby there is generated a problem that parts such as the spring 40 within the spring chamber 35 and a retainer clamping the diaphragm 33 are corroded.
In particular, in the case of the corrosion of the spring 40, a spring characteristic tends to be changed and there is a case that the pressure regulating operation of the pressure regulator is affected. Further, in the case that the upper housing 32 protrudes above the cover 22, it is hard to make a whole height of the vapor separator V small, so that a design freedom for arranging the vapor separator V within an engine cowling is low.
Further, in accordance with the second example of the conventional fuel injection apparatus, since the pressure regulator R is arranged at a position below the fuel liquid surface Xxe2x80x94X of the vapor separator V, the spring chamber 35 and the chamber 21 are arranged below the fuel liquid surface Xxe2x80x94X, and the spring chamber 35 communicates with the fuel within the chamber 21 via the vent hole 41. Further, the fuel within the chamber 21 is applied also to the return fuel hole 37 in the downstream side of the return valve seat 38.
In accordance with the structure mentioned above, when a great gravitational acceleration is applied to the vapor separator V at a time of driving the marine engine, the gravity of the fuel stored within the vapor separator V is greatly applied to the spring chamber 35 and the return fuel hole 37, whereby the pressing force of the spring 40 to the diaphragm 33 and the force applied to the valve body 39 from the return fuel hole 37 are changed, and an appropriate pressure regulating operation of the pressure regulator R is temporarily obstructed.
Further, since a piping length is necessarily increased in the regulator fuel pipe 45 communicating the pressure fuel inflow passage 42 connected to the fuel inflow hole 36 of the pressure regulator R with the fuel distribution pipe D or the fuel discharge pipe 44, a freedom of arranging the vapor separator V within the engine cowling is inhibited.
A fuel injection apparatus for a marine engine in accordance with the present invention is made by taking the problem mentioned above into consideration, and an object of the present invention is to provide a vapor separator which can stably carry out a pressure regulating operation of a pressure regulator arranged in the vapor separator for a long time period, and is made compact so as to have a high freedom of being arranged within an engine cowling.
In order to achieve the object mentioned above, in accordance with the present invention, there is provided a fuel injection apparatus for a marine engine in which pressure of fuel within a fuel tank is increased by a low pressure fuel pump, and the fuel is supplied into a vapor separator within which a fixed fuel liquid surface is formed, and
in which pressure of fuel within the vapor separator is increased by a high pressure fuel pump and is regulated to predetermined fuel pressure by a pressure regulator, and the fuel having the predetermined pressure is supplied toward a fuel injection valve,
wherein a casing of the vapor separator is formed by bringing a chamber which is formed in a cup shape and is open in the upper side, into contact with a cover which is formed in a cup shape and is open in the lower side so as to close an upper opening of the chamber, and
wherein the pressure regulator is arranged within a recess portion formed above a mounting collar portion of the cover and is arranged above the fixed fuel liquid surface and in a state in which the longitudinal axis of the pressure regulator is approximately parallel to the fuel liquid surface, a pressure fuel inflow passage toward the fuel chamber of the pressure regulator is formed so as to be branched from the fuel discharge passage within the cover, and a vent hole open to a spring chamber of the pressure regulator is open toward a lower position in the gravitational direction.
In accordance with the structure mentioned above, since the pressure regulator is arranged within the recess portion of the cover and above the fixed fuel liquid surface of the vapor separator, it is possible to shut off the pressure regulator from the ambient air.
Further, since the pressure regulator is arranged within the recess portion of the cover and in the state in which the longitudinal axis thereof is approximately parallel to the fuel liquid surface, it is possible to restrict an overall height of the vapor separator low.
Further, since the pressure fuel inflow passage is formed so as to be branched from the fuel discharge passage within the cover, it is possible to abolish the regulator fuel pipe and it is possible to make the fuel piping simple.
Further, since the pressure regulator is arranged above the fuel liquid surface within the recess portion, and the vent hole open to the spring chamber is open toward the lower position in the gravitational direction, it is possible to immediately discharge the fuel from the spring chamber even if the fuel enters into the spring chamber due to agitation of the fuel within the vapor separator.